1. Field of the Invention
The present invention relates to methods and apparatus for circulating and selectively supplementally heating large volumes of air in industrial facilities and the like.
2. Prior Art
Industrial facilities including warehousing, fabrication, machining and assembly areas typically have relatively high ceilings to accommodate the operation of hoists, lift trucks, overhead conveyors, and other industrial equipment. Heated air rises and accummulates near high ceilings. While a heating system is laboring to maintain 65.degree. F. at body level in a high-ceilinged room, ceiling temperature may reach 88.degree. F. or above. Most heating systems do little to return ceiling air into body level circulation, and as such, the high temperature ceiling air represents a substantial loss of energy.
Proposals have been made to heat warehouses and other large industrial buildings with ductless furnaces positioned along walls or near corners of the building. One furnace proposed for such use has a modular construction including a lower intake section, an intermediate heater section, and an upper discharge section. One drawback of the proposed furnace is that its being positioned near walls or in a corner of the room it serves inhibits its drawing ceiling air efficiently into circulation. An other drawback is that its air inlet and discharge openings are not provided around the entire periphery of the inlet and discharge sections to permit an efficient, radially directed intake and discharge of air. The non-radially directed intake and discharge flow paths that result due both to the configuration of the intake and discharge sections and due to the positioning of the proposed furnace along a wall or in a corner, provide inefficient air circulations that often do not reach all portions of the room being heated and are readily disturbed by obstructions as columns, low partitions, and nearby machinery.
A problem commonly encountered in industrial facilities is that activities conducted in different areas are subject to change from time to time, as demand increases and decreases for certain types of products and services. While activities conducted in an area of an industrial facility may change relatively substantially, it is unusual for accommodating changes to be made in the area's heating system. Heating systems are ordinarily permanently installed and, while their output can be controlled within a range to provide some accommodation for a change in heat demand, such systems seldom include provisions to enhance air circulation in and provide supplemental comfort heating for a specific area where activities are temporarily concentrated.
Portable heaters of various types have been proposed to supplement the operation of existing heating systems. A drawback of such proposals is their inability to gently and effectively circulate large volumes of air in a designated area. Proposed portable heaters are expensive to operate and tend to provide an uncomfortable working atmosphere with hot air concentrated near the heaters and with a substantially colder air environment only a few feet away. Where proposed portable heaters have relatively large air circulating capabilities, they have typically been noisy in operation and provide directional high velocity heated air outputs that are objectionable. Moreover, proposed portable heaters do practically nothing to bring high temperature ceiling air back into circulation.